The answer is approximately 30%. Groundwater also comprises 1.7 percent of all of Earth's water. There is about 5,614,000 cubic miles (mi3), or 23,400,000 cubic kilometers (km3), of groundwater on Earth. About 54 percent is saline (occurring in aquifers below the oceans), with the remaining 2,526,000 mi3 (10,530,000 km3) , about 46 percent, being freshwater.